ISS006-E-28546 (16 February 2003) --- Popocatepetl and Iztaccíhuatl Volcanoes in Mexico are featured in this digital image photographed by an Expedition 6 crewmember on the International Space Station (ISS). As part of the circum-Pacific “Ring of Fire”, Mexico hosts several of the world’s most continually active volcanoes including the massive Popocatepetl (Aztec for “Smoking Mountain”). This detailed oblique photograph also depicts a neighboring volcano, Iztaccíhuatl (the “Woman in White”). Popocatepetl has produced small, intermittent eruptions since 1994. In addition to the constant potential of eruptions producing ash deposits, pyroclastic flows, and lava, the summit of Popocatepetl also hosts glaciers. These can melt during eruptions to form mudflows that blanket areas to the south. In contrast to Popocatepetl’s well-defined symmetrical cone, Iztaccíhuatl is formed from several overlapping smaller cones that trend north-northwest to south-southeast. Glaciers and year-round snow are also present on Iztaccíhuatl (white regions along the peaks). According to NASA scientists, deep valleys have been eroded into the massive apron of ash and pumice deposits, glacial outwash, and alluvium to the east of the volcano. Despite its close proximity, similar age, and similar geologic character to Popocatepetl, Iztaccíhuatl has not erupted in historic times. This has encouraged the establishment of numerous agricultural fields (visible as faint rectilinear patterns in the lower half of the image) on the eastern flank of the mountain.